A Locomotive Cylinder Machining Question

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Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

A Locomotive Cylinder Machining Question

Post by Carrdo »

Does anyone have a description and/or photos of how a two piece locomotive cylinder casting for piston valves is laid out and set up on a vertical milling machine?

I am looking for the first/initial steps/setup's only (up to the important first few cuts) as if one gets this wrong everything else which follows will also be wrong.

I have not seen this described in detail on Chaski or elsewhere but if it exists, just let me know.
Last edited by Carrdo on Sat Jan 07, 2017 12:49 pm, edited 1 time in total.
FLtenwheeler
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Re: A question

Post by FLtenwheeler »

What cylinders are you working with?

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
Carrdo
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Re: A question

Post by Carrdo »

Hi Tim,

All are 3/4" scale. One set happens to be Hoffman (the middle set), one set happens to be Coventry (the top set) and one cylinder casting is unknown (bottom, single) from my unknown cylinder patterns. See photo.
Attachments
Raw Cylinder Castings.jpg
Andy Rafferty
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Re: A question

Post by Andy Rafferty »

My first step is make a plug to fit the rough cyl. bore and extend proud as tall as your mill will allow. Jack shim and clamp to produce the best x-y you can get. Face the cylinder and get a quick bore scribe a light center line for the bore x-y. Repeat for the Left side (right is always my first). Flip each cyl. block shim the faced surface above the table and clamp with your x-y scribe close. Face the mating surfaces equally to get your center to center of the main bores correct. key and indicate your bolt holes for the mating surfaces. Pull it all down, the keys or pins will keep you square. Bolt the haves together, square the center lines to the table AND GO FOR IT. Ask ten others I'm sure you will get twelve other ways that will work better. Have Fun!
little giant
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Re: A Locomotive Cylinder Machining Question

Post by little giant »

At www.karlkobel.com shows you how to machine 1.6 scale Mikado cylinders same type of procedure just smaller.
KarlKobel
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Re: A Locomotive Cylinder Machining Question

Post by KarlKobel »

Little Giant,

Thanks for the mention.

Karl
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VO4454
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Re: A Locomotive Cylinder Machining Question

Post by VO4454 »

Hello Carrado,

Here is a very informative link to Jack Bodemann's post on the machining of the cylinders for his Friends 0-6-0. I would think the Coventry castings are quite similar to the new castings available from John at Friends'.

Vic

http://www.chaski.org/homemachinist/vie ... +Cylinders
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ACyl1.JPG
ACyl1.JPG (22.6 KiB) Viewed 4535 times
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Carrdo
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Re: A Locomotive Cylinder Machining Question

Post by Carrdo »

Thanks to all who have replied answering my question.

I have obtained additional information from Karl Kobel on the initial setup to machine the first cut (the joint faces on his half cylinder castings) and have now written out a detailed procedure on this.

Jack Bodenmann's previous posts on Chaski with photos concerning the machining of his Friends, 0-6-0, 3/4" scale switcher half cylinder castings is likewise most informative and detailed.

Starting in the April,1954 issue of the Miniature Locomotive, Henry Coventry also provided a very detailed procedure for the machining of his B&O 0-6-0 Switcher half cylinder castings in 3/4" scale. His method was based on using the popular 9" SB lathe.

It is interesting to note that if one studies the 1954 Coventry method, which utilizes the lathe faceplate and if one envisions rotating the faceplate through 90 degrees and this now becomes the table of a vertical mill, all of the above methods for machining model locomotive cylinder half castings are essentially the same. Previous to this, Martin Lewis of the original Little Engines in the 1930's described a similar lathe based method and even earlier (late 1920's) L.B.S.C.probably was the first to do so.

Unfortunately, the two outside casting ribs used to aid in the initial setup/machining on the original Coventry/Friends half cylinder castings are not present on the Hoffman cylinder castings so a slightly modified procedure has to be employed.

With all of the above now available, my file on locomotive cylinder machining has become rather thick; so there now is no excuse whatsoever for not doing it right.
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